1. Field of the Invention
The present invention relates to padmounted electrical distribution transformers and in particular to a tank for such transformers.
2. Description of the Prior Art
A transformer tank is designed to house a transformer electrical core and coils. Conventional tanks are formed in the shape of rectangular cube and comprise four vertical sidewalls, a horizontal top wall, hereinafter referred to as a tank cover, and a horizontal bottom wall. During the assembly, five of the walls are preassembled together by welding, leaving an opening to permit subsequent insertion of the core and coil assembly. Normally the opening is provided at the top, although in some cases it can be provided at one of the sides. After the open tank has been tested for leaks and coated with a corrosion resistant paint, the transformer core and coil assembly is placed inside the tank through the top. The tank is then filled with oil and the top wall, the tank cover, is placed on flanges formed by bent upper ends on each of the side panels and is welded in place. During the cover welding operation, the heat generated by the weld is high enough so as to possibly damage or even burn the coated surfaces of the tank flange which will require additional repair work. The prior art technique for protecting the painted surface from the heat during the welding operation is disclosed in U.S. Pat. No. 4,559,699--Owen et al. In that patent it will be noted that an extra steel bar is welded to the tank flange to act as a heat shield when the tank cover is welded in place on the tank. This is a very expensive process in manufacturing transformer tanks.
It would be desirable to eliminate the extra operation of welding a steel bar to the tank flange so as to reduce the manufacturing costs.